Method and Apparatus for Transmitting and Receiving Data by Relay Node in Wireless Communication System

1. A method for transmitting and receiving data by an Integrated Access and Backhaul (IAB) node in a wireless communication system, the method comprising: receiving, from a child node, data units; generating a STATUS Protocol Data Unit (PDU) when a reception failure of one or more data units is detected; transmitting, to the child node, the STATUS PDU including Negative Acknowledgement (NACK) information corresponding to the one or more data units of which the reception failure is detected, wherein the STATUS PDU does not include ACK information for the data units which are successfully received, wherein an acknowledgement state variable of the child node is not updated based on the STATUS PDU including a field instructing that the acknowledgement state variable of the child node is not to be updated, or the acknowledgement state variable of the child node is not updated based on a smallest Sequence Number (SN) among SNs related to the NACK information being different from the acknowledgement state variable.

2. The method of claim 1 , further comprising: receiving the one or more data units retransmitted from the child node.

3. The method of claim 1 , wherein: the STATUS PDU includes a Control PDU Type (CPT) field set to a specific value indicating that the STATUS PDU does not include the ACK information for the data units which are successfully received, or the STATUS PDU includes an ACK SN field set to a specific value indicating that the STATUS PDU does not include the ACK information for the data units which are successfully received, or the STATUS PDU includes the ACK SN field set to a value which is equal to or less than a smallest SN among SNs of the NACK information of which the reception failure is detected, or the STATUS PDU includes the ACK SN field set to a value which is equal to or less than a biggest SN among the SNs of the NACK information of which the reception failure is detected.

4. An Integrated Access and Backhaul (IAB) node for transmitting and receiving data in a wireless communication system, the IAB node comprising: a memory; and at least one processor coupled to the memory and configured to: receive, from a child node, data units; generate a STATUS Protocol Data Unit (PDU) when a reception failure of one or more data units is detected; transmit, to the child node, the STATUS PDU including Negative Acknowledgement (NACK) information corresponding to the one or more data units of which the reception failure is detected, wherein the STATUS PDU does not include ACK information for the data units which are successfully received, wherein an acknowledgement state variable of the child node is not updated based on the STATUS PDU including a field instructing that the acknowledgement state variable of the child node is not to be updated, or the acknowledgement state variable of the child node is not updated based on a smallest Sequence Number (SN) among SNs related to the NACK information being different from the acknowledgement state variable.

5. The IAB node of claim 4 , wherein the at least one processor is further configured to: receive the one or more data units retransmitted from the child node.

6. The IAB node of claim 4 , wherein: the STATUS PDU includes a Control PDU Type (CPT) field set to a specific value indicating that the STATUS PDU does not include the ACK information for the data units which are successfully received, or the STATUS PDU includes an ACK SN field set to a specific value indicating that the STATUS PDU does not include the ACK information for the data units which are successfully received, or the STATUS PDU includes the ACK SN field set to a value which is equal to or less than a smallest SN among SNs of the NACK information of which the reception failure is detected, or the STATUS PDU includes the ACK SN field set to a value which is equal to or less than a biggest SN among the SNs of the NACK information of which the reception failure is detected.

7. The IAB node of claim 4 , wherein the at least one processor is further configured to implement at least one advanced driver assistance system (ADAS) function based on signals that control a User Equipment (UE).

8. The IAB node of claim 4 , wherein the IAB communicates with at least one of user equipment (UE), a UE related to an autonomous driving vehicle, a base station and/or a network.